### De Broglie Wavelength

Posted:

**Sun Oct 09, 2016 2:25 pm**When calculating the de broglie wavelength will the problem always specifically say to "calculate the de broglie wavelength?" if not how do we know when to use it?

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=18&t=15790

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Posted: **Sun Oct 09, 2016 2:25 pm**

When calculating the de broglie wavelength will the problem always specifically say to "calculate the de broglie wavelength?" if not how do we know when to use it?

Posted: **Sun Oct 09, 2016 2:27 pm**

You use the de Broglie wavelength when calculating the wavelength for a particle that has mass, such as an electron.

Posted: **Sat Jul 01, 2017 9:25 pm**

Will frequency always be given in problems that ask to calculate wavelength?

Posted: **Sun Jul 02, 2017 9:24 pm**

The De Broglie equation doesn't require frequency?? Unless you meant velocity, in which case yes that should be given if the wavelength is unknown.

Posted: **Sun Jul 02, 2017 9:43 pm**

in quantum mechanics description of an atom, it was mentioned that e- have discrete energies with only certain wavelengths allowed inside an atom... will this be given or are we required to find it?

Posted: **Sun Jul 02, 2017 9:50 pm**

by using De Brogile's equation will it be able to tell us if the wavelength is constructive or destructive

Posted: **Sun Jul 02, 2017 9:57 pm**

would we ever need to calculate De Brogile's Wavelength to find if its an allowed energy level or not allowed energy level?

Posted: **Fri Oct 13, 2017 11:27 am**

What does it intuitively mean when we find the wavelength of large everyday objects? For example, in problem 1.35, what does it really mean when we compare the wavelengths of a 60kg person vs an 80kg person? Or if we calculate the wavelength of a baseball traveling 92 mph in problem 1.39? Do these have real-world application? Will we ever have to know what this means or just calculate the value?

Posted: **Mon Oct 16, 2017 9:20 am**

The wavelength of an object directly relates to how energetic the wave is. Being able to calculate and knowing the wavelength is helping in determining how "powerful" the wave is and if it is safe (radio, microwave, visible light, etc.) or dangerous (gamma rays, x-rays, UV radiation).

Posted: **Mon Oct 16, 2017 11:23 am**

What is the smallest wavelength that can be detected?

Posted: **Mon Oct 16, 2017 5:23 pm**

Isn't it approx. 420nm?

Posted: **Tue Oct 17, 2017 9:45 pm**

An important thing to note: photons don't have mass! That's why none of the other formulas include mass or velocity. You'll know when to use de broglie because you'll be given mass or velocity and it's the only formula that you can plug this into to find wavelength. Hope this helps!

Posted: **Wed Oct 18, 2017 10:25 am**

Calculating the de Broglie wavelength will not tell you if it is constructive or destructive. It just simply tells you how long the wavelength is.

Posted: **Wed Oct 18, 2017 10:31 am**

In 1.35, assuming the velocities of the two people are similar, I think the problem is just trying to show the relationship between the de Broglie wavelengths of two objects of the same speed but different masses, that being that the object with the smaller mass will have the larger de Broglie wavelength.

In terms of 1.39, I think this problem is mainly aimed at unit conversion and then using the appropriate converted units in the de Broglie equation. However, as seen in some of the online module questions for de Broglie, you are sometimes asked whether the wavelength is detectable or not. This is the only application I could think of.

In terms of 1.39, I think this problem is mainly aimed at unit conversion and then using the appropriate converted units in the de Broglie equation. However, as seen in some of the online module questions for de Broglie, you are sometimes asked whether the wavelength is detectable or not. This is the only application I could think of.

Posted: **Fri Oct 20, 2017 2:12 pm**

When dealing with the De Broglie wavelength, usually the question will include a velocity or a mass of the particle being used (or say that it's an electron or something else with a known mass). This equation deals with particles that are not moving at the speed of light, so if the particle discussed is not a photon, and asks for energy, velocity, or mass while giving the value for the other two of those it is likely De Broglie.

Posted: **Tue Nov 05, 2019 6:23 pm**

At what de Broglie wavelength can the wavelike properties be detected?

Posted: **Tue Nov 05, 2019 10:29 pm**

I believe that everything larger than 10^-12 is a detectable way.

Posted: **Tue Nov 12, 2019 12:36 am**

De Broglie's wavelength equation applies to any moving particle with momentum so that the particle has wavelike properties, such as electrons, neutrons, and protons. However, only when the particle has extremely small mass would the wavelike property be noticeable.

Posted: **Fri Nov 15, 2019 10:21 pm**

Most likely the problem is not gonna tell you which equation to use, but you can use de broglie when there’s mass.

Posted: **Fri Nov 15, 2019 10:24 pm**

I think the short and direct answer to this question is no, the question will not always say De Broglie in it. You need to know the components of the equation to know when to use it.

Posted: **Sat Nov 16, 2019 10:38 am**

You would use de Broglie whenever you're dealing with a particle that is not light, and has mass.

Posted: **Wed Dec 04, 2019 6:26 pm**

Can you use the de broglie equation to calculate the wavelength of something other than an electron? And when do we know to use the de broglie equation over KE?

Posted: **Wed Dec 04, 2019 8:02 pm**

you can use de Broglie for something other than an electron (its anything that has mass), but i think were mostly expected to use it for electrons. im pretty sure the problem would clearly state the mass of another particle if they expected us to do that

Posted: **Wed Dec 04, 2019 8:04 pm**

You can use the de Broglie equation for other things, if they have mass. keep in mind that this means the de Broglie equation cannot be used for photons because they do not have mass.